1. Field of the Invention
The present invention is in the field of Orthopedic implants, and in particular is directed to a novel yet simple bone plate improvement whereby a controllable compression capability is instilled in the bone plate.
2. Description of the Related Art
Bone plates are well-known in the Orthopedic arts, having been used to repair skeletal system injuries or corrective modifications since the earliest days of orthopedic surgery. Bone plates are also the subject of numerous patents, with over 130 issued US patents issued with the term “bone plate” in their titles since 1976. Generally, a bone plate is a stiff yet malleable low-profile shaped element with perforations for accepting bone screws or anchors. Usually metallic in nature, a boneplate is used to stabilize one or more bones that have been fractured in accidents and that need temporary or permanent external support during the healing process. Bone plates have been created for just about any bone fracture situation imaginable, from typical long bone fractures that occur in the femur to specialized plates devised to stabilize various vertebrae of the spinal column.
A typical modern bone plate is depicted in U.S. Pat. No. 7,740,648 (Young et al.) that is directed to a bone plate apparatus particularly suited to tibial plateau-leveling osteotomy and a distal femoral osteotomy. The bone plate has a main longitudinal axis, a bone-contacting bottom side (not shown) and a top side with at least three sets of overlapping holes which communicate through the plate from the top to the bottom side. The sets of overlapping holes define threaded apertures having multifaceted surfaces. When applied to a bone, two sets of such overlapping holes are located so as to lie on opposite sides of an osteotomy site and on the tibial plate; a third is aligned at approximately 60 degrees with the longitudinal axis. Compression of bone fragments is described at the fracture site across the line 112 when bone screws 24 having beveled surfaces 120 and 122 (preferably having no thread 30 on the head 26) enter the apertures and are torqued down such that wedging action takes place at the interface between the beveled surfaces and the chamfered surfaces 102 and 104. The degree of wedging attainable by this design is limited by careful prepositioning and installation because there is little ability to change the degree of wedging after installation except by advancing or reversing the screws which could impact the final plate-bone conformity.
What is needed is a simple yet reliable device for applying lateral stability and adjustable compression to a fracture or osteotomy site that does not rely upon bone anchor placement.